1. Computer Networks 0110-IP Gergely Windisch windisch.gergely@nik.uni-obuda.hu

2. IP Address Why do we need addresses? How IP addresses look like IP Classes (sorta’) Addressing modes – unicast, multicast, broadcast ARP – connecting physical and logical addresses – RARP – doing the same but the other way around Private IP addresses Classless inter-domain routing (CIDR) DHCP – configure network parameters automatically

3. Routing Direct and indirect data transfer Connecting networks routing, routers transmission control protocols MPLS -

4. IPv6 Similar, only better

5. Store and forward packet switching Packets are transferred from source to destination through routers along the way. Packet is stored until it is fully received (cheksummed and everything) – Once it is received it is forwarded to the next hop

6. Network layer Connectionless or connection oriented? Connectionless – treat each packet individually Connection oriented – create virtual circuit

7. Connectionless

8. Connection oriented

9. Comparison

10. Setup time vs. routing time Connection oriented may be useful for VPN, or other long term connection

11. Routing algorithms Routing algorithm decides where (which port) an outgoing packet should be sent to Routing vs forwarding – forwarding is the actual act of sending the package – routing is the algorithm that fills/updates the table that is used with the forwarding Routing algorithms – nonadaptive (static) routing routing table is filled in advance without any consideration to changes – adaptive (dynamic) routing routing table is calculated on the fly

12. Routing algorithms Shortest path – shortest path is selected Flooding – all incoming packages are sent out to all ports Distance vector routing – distance vectors to all other routers are kept Link state routing

13. Routing algorithms (2) Distance vector routing – count to infinity problem bad news travels slowly - when router A is gone, router B (in (b) - line 3) still thinks that it can reach it via C in 3 hops

14. Network layer in the Internet

15. IP (Internet Protocol) – provide a best effort transportation from source to destination without any consideration as to whether the machines are on the same network or on very different networks

16. IPv4 datagram

17. Some IP options

18. IP Addresses IP address identifies network interface, not host Hierarchical address – prefix – network id – host id Hierarchy makes routing simpler – routing tables need only store the networks, not the individual machines

19. IP address

20. Subnet / CIDR Subnets help create smaller networks CIDR (classless interdomain routing) helps define larger networks

21. Subnet There may come a time when multiple departments of a university will want to get on the internet They already have a /16 address, so the options would be – put all the departments in one network (142.124.0.0) not so good – buy new IP ranges at Walmart* (142.125.0.0,..126…...127….. and so on) works, but costs a lot and wastes a whole bunch of IP addresses along the way – Enter Subnets *: Not really at Walmart at all

22. Subnets

23. CDIR Many networks -> lots and lots of lines in the routing tables – computers and routers in an organization have default gateways - some routers on the network don't. Enter route aggreagation

24. Route aggreagation example (1)

25. Route aggreagation example (2)

26. Classful IP addressing

27. Special addresses

28. Addressing modes Unicast Multicast Broadcast

29. Private IP addresses Anyone can use them, but no private address may appear on the internet 10.0.0.0 – 10. 255.255.255 / 8 172.16.0.0 – 172. 31. 255. 255 / 12 192.168.0.0 – 192.168.255.255 / 16

30. Network Address Translation

31. Automatic configuration - DHCP Manual configuration is error prone (and labour intensive – something any self-respecting admin wishes to avoid)

32. IPv6 IPv4 addresses are now long gone. And other problems. Main aims of v6 – Support billions of hosts – Reduce the size of the routing tables – Simplify protocol (faster processing) – Better security – Distinguish types of services – Better multicasting – Mobile devices – allow roaming – Somewhat compatible with current solution

33. IPv6 in detail 128 bit address – More than enough* Simplified headers (7 fields instead of 13 in IP) Better options handling - more closely described options - easy way for routers not to look at them - faster processing Better security - authentication and privacy features More QoS (Quality of Service) *: so is 640k

34. IP v6 packet

35. IPv6 address

36. More on IP v6 later – if we have the time, that is.